1. Field of the Invention
This invention relates to gas lift apparatus and more particularly to side pocket mandrels for use in wells produced by gas lift techniques.
2. Description of the Prior Art
Side pocket mandrels typically have an elongated body with a main bore extended longitudinally therethrough and a receptacle bore extending alongside the main bore and a belly portion above the receptacle bore to provide space for the operation of a kickover tool with which a flow control device is installed in or removed from the receptacle bore. The receptacle bore in most cases is provided with lateral ports which communicate the receptacle bore with the exterior of the side pocket mandrel so that a flow control device placed in the receptacle bore will control the passage of lift gas between the interior of the tubing string in which the side pocket mandrel is connected and the tubing-casing annulus surrounding the tubing string. For some time now, many side pocket mandrels have been equipped with deflectors for protecting the upper end of the receptacle bore and any flow control device disposed therein from damage due to being impacted by well tools passing through the tubing string. The deflectors will cause large ordinary well tools to be deflected back into the main bore of the side pocket mandrel while the smaller diameter tools which are intended to enter the receptacle bore will be guided thereinto by such deflectors. Examples of side pocket mandrels having deflectors are illustrated in the following U.S. Pat. Nos.,
______________________________________ 3,268,006 3,891,032 4,031,954 4,106,564 4,333,527 3,741,299 3,874,445 4,034,806 4,197,909 4,407,362 3,796,259 4,002,203 4,066,128 4,201,265 4,462,465 3,802,503 4,030,543 4,106,563 4,239,082 4,480,686 3,807,498 ______________________________________
Deflectors normally have been manufactured separately from the side pocket mandrel body and then welded therein either as a part of a receptacle unit or welded directly to the side pocket mandrel body.
U.S. Pat. No. 3,268,006 issued Aug. 23, 1966 to W. J. Hayes and discloses side pocket mandrels having deflectors therein extending upwardly from the upper end of the receptacle bore for some appreciable distance. The deflectors provide a channel which is narrower than the main bore but is sufficiently wide to guide a flow control device or the like into the receptacle bore thereoelow. Tools which are too wide to enter the channel provided by the deflector will be kept clear of the receptacle bore and will be deflected back into the main passage through the side pocket mandrel.
U.S. Pat. No. 3,741,299 which issued June 26, 1973 to Ben D. Terral discloses a type of deflector which is welded into the body of the side pocket mandrel just above the receptacle but adjacent thereto. The receptacle and the deflectors are made separately and then are welded into a window in the wall of the side pocket mandrel body. The deflector provides a channel which will guide smaller tools into the receptacle bore and is provided with an upwardly and outwardly sloping surface for deflecting larger tools away from the receptacle bore and into the main bore. Many other patents show deflectors of the type which have been disclosed in U.S. Pat. No. 3,741,299, and among these are the following U.S. Pat. Nos.:
______________________________________ 3,796,259 3,802,503 3,807,498 3,874,445 3,891,032 4,002,203 4,030,543 4,031,954 4,034,806 4,106,563 4,106,564 4,197,909 4,201,265 4,239,082 4,480,686 ______________________________________
U.S. Pat. No. 4,066,128 which issued to Jerry B. Davis and Guy W. Gant on Jan. 3, 1978 discloses deflectors which are welded into the side pocket mandrel just above the receptacle bore to deflect larger tools away from the receptacle bore while guiding smaller tools into the receptacle bore. Similar deflectors are shown in U.S. Pat. Nos. 4,407,362 and 4,462,465.
U.S. Pat. No. 4,197,909 issued Apr. 15, 1980 to Ben D. Terral, and this patent illustrates deflectors which are very similar to those in U.S. Pat. No. 3,741,299 mentioned earlier, and in addition to this, the mandrel body immediately above the upper ends of the deflectors has been provided with a pair of internal button-like projections which will prevent tools from interfering with or lodging atop the upper ends of the deflectors. Sometimes deflectors can be spaced slightly from the inner wall of the mandrel leaving a crack or a crevice therebetween in which tools or wire may become fouled. The internal buttons taught in U.S. Pat. No. 4,197,909 are provided to prevent this from happening. One form of these buttons is illustrated in FIG. 3 of U.S. Pat. No. 4,197,909 and shows that these buttons are formed by making an external indentation in the wall of the mandrel body and causing a corresponding inward projection or button.
U.S. Pat. No. 4,333,527 issued June 8, 1982 to Robert S. Higgins and David T. Merritt, and this patent discloses deflectors which are welded in place within the upper body section of the side pocket mandrel which is then welded by a circumferential weld to the upper end of the lower body section.
Deflectors for side pocket mandrels are of a shape which is costly to manufacture and welding them in place within the mandrel is generally expensive. Sometimes the deflectors have their upper ends spaced slightly from the inner wall of the mandrel, thus leaving a crevice in which tools or wire can lodge and cause trouble. If the deflectors are welded into the mandrel through use of plug welds, these plug welds can become a source of mandrel failure since they may crack due to flexure resulting from differential pressures which may act in one direction or the other, inwardly or outwardly.
None of the prior art patents listed and with which the inventor is familiar shows a side pocket mandrel having deflectors formed in the wall thereof above the receptacle bore providing a channel between them which is narrower than the main bore but wider than the receptacle bore for guiding a flow control device into the receptacle bore and providing upwardly facing inclined deflecting surfaces for deflecting other larger well tools toward the main bore and away from the receptacle bore and any flow control device which may be disposed therein.